Assuming 2KWh / mile average consumption[1], an EV semi powertrain would be pulling ~120KW continuously from the battery. Even at 90-95% efficiency, there will be 6-12KW of waste heat available in the powertrain, more than enough to heat the cabin in cold weather. Modern EVs actually do scavenge waste heat from the battery and motors for cabin heating[2], unlike the EVs tested in the cited article.
But even without using the available waste heat, a 6KW resistive cabin heater would only use 18KWh over a 3 hour drive. For a cheap passenger EV, this could be 20-40% of the battery, but for a semi with 500 miles of range, 18KWh would only be 1-3% of the battery.
Put more succinctly, the battery in an EV semi would be 5-10x larger than the battery in a passenger EV, but the energy required to heat the cabin will be roughly the same. So the effect of cabin heating on range loss would be 5-10x less on a EV semi than a passenger EV.
I would remove this line from your post: "plus the batteries lose > 40% of their range in cold weather" because I don't think that claim is supported by any source, or by basic logic and math, in the context of a semi truck.
[1] https://www.tesla.com/semi [2] https://jalopnik.com/the-tesla-model-ys-octovalve-and-coolin...